Cyclophyllum barbatum is a species of flowering plant in the family Rubiaceae. It is a shrub or tree native to the South Pacific, including the Caroline Islands, Cook Islands, Fiji, Marquesas Islands, Pitcairn Islands, Samoan Islands, Society Islands, Solomon Islands, Tonga, Tuamotu Archipelago, Tubuai Islands, and Vanuatu. It has been introduced to Hawaii.
On Rarotonga in the Cook Islands it is common in Homalium forest on lower mountain slopes, dominated by the endemic tree Homalium acuminatum.
In the Marquesas Islands it is a common understory shrub or tree in mid-elevation forests from 300 to 800 meters elevation and with an average annual rainfall of 2,000 to 3,000 mm.